Methods for fluid flow through body passages

ABSTRACT

A device includes a first end portion, a second end portion, an intermediate portion between the first end portion and the second end portion, and a graft material coupled to at least the intermediate portion. The first end portion has a first end diameter. The second end portion has a second end diameter larger than the first end diameter. The intermediate portion tapers between the first end portion and the second end portion. A method of diverting fluid flow from a first passage to a second passage comprising deploying the device in a third passage between the first passage and the second passage, expanding the first end portion against sidewalls of the first passage, and expanding the second end portion against sidewalls of the second passage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/718,477, filed May 21, 2015 and issued as U.S. Pat. No. 9,326,792 onMay 3, 2016, which is a continuation of U.S. patent application Ser. No.14/592,163, filed Jan. 8, 2015 and issued as U.S. Pat. No. 9,108,018 onAug. 18, 2015, which is a divisional of U.S. patent application Ser. No.13/791,185, filed Mar. 8, 2013, which is a continuation-in-part of U.S.patent application Ser. No. 12/297,498, issued as U.S. Pat. No.8,439,963 on May 14, 2013 and filed under §371(c) on Feb. 25, 2009 as aU.S. national stage of PCT Patent App. No. PCT/GB2007/001430, filed onApr. 20, 2007, the contents of which are incorporated herein byreference in their entirety, which claims priority to GB 0607761.4,filed Apr. 20, 2006.

BACKGROUND

The present application relates to devices and methods and for use inpercutaneous interventional surgery. In particular, the presentapplication relates to devices and methods for providing or maintainingfluid flow through passages such as heart cavities and blood vessels.

Minimally invasive percutaneous surgery, commonly known as “key-hole”surgery, is a well-known surgical technique wherein surgical devices areinserted into a patient's body through a small aperture cut. Forexample, it is often preferable to use key-hole surgery incardiovascular procedures, so as to avoid the substantial discomfort,need for general anesthesia, trauma, high risk of infection, and longrecovery time typically associated with conventional surgery.

Key-hole surgery is often used in the treatment of coronary heartdisease, in which a coronary artery is partially occluded by a blockagesuch as an atheroma. For example, in balloon angioplasty, a ballooncatheter including a flexible, hollow tube is inserted into an artery,usually near the patient's groin, and is guided through the body to thepatient's heart. The heart and the cardiac arteries may be visualisedusing X-ray fluoroscopy, and the tip of the catheter may be fluorescentso that its position can be determined. The catheter carries aninflatable balloon near its distal tip. The balloon is positioned in ornear to the blockage, and then the balloon is inflated so as to widen ordilate the occluded blood vessel to restore blood flow through thecoronary artery to the cardiac tissue.

A tubular supporting device (e.g., stent) may be deployed at the site ofthe blockage to prevent future occlusion (restenosis) or collapse of theblood vessel. The stent may, for example, be an expandable metal meshtube which is carried on the balloon of the balloon catheter. While onthe catheter, the tube has a relatively small diameter in comparison tothe diameter of the blood vessel. The stent expands when the balloon isinflated, so that the stent pushes against the wall of the blood vessel.The stent is arranged to retain its expanded shape when it reaches itsexpanded position, for example by plastic deformation or by means of amechanical locking mechanism, so as to form a resilient scaffold orsupport in the blood vessel. The support structure (e.g., stent)supports and dilates the wall of the blood vessel to maintain a pathwayfor blood to flow through the vessel. Self-expanding stents are alsoavailable, which are held in a collapsed state by a suitably adaptedcatheter for transport through the artery and which adopt an expandedstate when deployed at the site of the blockage. The catheter may, forexample, include a retaining sleeve which retains the stent in acompressed or unexpanded state. Upon removal or withdrawal of the sleevefrom the stent, the stent expands to support and dilate the wall of theblood vessel.

In acute cases of coronary heart disease, where a coronary artery isseverely or completely occluded, angioplasty may not be suitable.Instead, coronary bypass surgery may be required. Bypass surgery is anopen-chest or open-heart procedure, and typically involves grafting apiece of healthy blood vessel onto the coronary artery so as to bypassthe blockage and restore blood flow to the coronary tissue. The healthyblood vessel is usually a vein harvested from the patient's leg or armduring the course of the bypass operation. To perform the procedure, thepatient's heart must be exposed by opening the chest, separating thebreastbone, and cutting the pericardium surrounding the heart, resultingin significant surgical trauma.

Certain patients are unsuitable as candidates for conventional coronarybypass surgery, due low expectation of recovery or high risk from thesignificant trauma due to surgery, high risk of infection, absence ofhealthy vessels to use as bypass grafts, significant co-morbidities, andexpected long and complicated recovery time associated with open-chestsurgery. For example, factors such as diabetes, age, obesity, andsmoking may exclude patients who are in need of treatment.

SUMMARY

Certain embodiments described herein can provide fluid flow in passagessuch as coronary and/or peripheral blood vessels by creating a bypassusing minimally invasive surgical techniques.

In some implementations, a method of diverting fluid flow from a firstpassage to a second passage comprises deploying a device in a thirdpassage between the first passage and the second passage. The devicecomprises a first end portion, a second portion, an intermediateportion, and a graft material. The first end portion has a first enddiameter. The second end portion has a second end diameter larger thanthe first end diameter. The intermediate portion is between the firstend portion and the second end portion. The intermediate portion tapersbetween the first end portion and the second end portion. The graftmaterial is coupled to at least the intermediate portion. The methodfurther comprises expanding the first end portion against sidewalls ofthe first passage and expanding the second end portion against sidewallsof the second passage.

The first passage may be an artery and the second passage may be a vein.The first passage may be a coronary artery and the second passage may bea coronary vein. The method may further comprise dilating the thirdpassage. The first passage may be a peripheral artery and the secondpassage may be a peripheral vein. The method may further comprisedilating the third passage. Dilating the third passage may compriseexpanding the intermediate portion. The first passage may besubstantially parallel to the second passage. The intermediate portionmay be conformable to an “S” shape. Expanding the first end portion andthe second end portion may comprise allowing self-expansion of the firstend portion and the second end portion. Expanding the first end portionand the second end portion may comprise balloon expanding at least oneof the first end portion and the second end portion. Expanding one ofthe first end portion and the second end portion may comprise allowingself-expansion of the one of the first end portion and the second endportion and expanding the other of the first end portion and the secondend portion may comprise balloon expanding the other of the first endportion and the second end portion. The method may further compriseexpanding the intermediate portion.

In some implementations, a device comprises a first end portion, asecond end portion, an intermediate portion, and a graft material. Thefirst end portion has a first end diameter. The second end portion has asecond end diameter smaller than the first end diameter. Theintermediate portion is between the first end portion and the second endportion. The intermediate portion tapers between the first end portionand the second end portion. The graft material is coupled to at leastthe intermediate portion.

At least one of the first end portion and the second end portion may besubstantially cylindrical. The first end portion may be substantiallycylindrical and the second end portion may be substantially cylindrical.The first end portion may taper between the first end diameter and theintermediate portion or the second end portion may taper between thesecond end diameter and the intermediate portion. The first end portionmay taper between the first end diameter and the intermediate portionand the second end portion may taper between the second end diameter andthe intermediate portion. The first end portion may comprise a firsttype of material, the second end portion may comprise a second type ofmaterial, and the intermediate portion may comprise a third type ofmaterial. The first type of material may comprise a first cut material,the second type of material may comprise a second cut material, and thethird type of material may comprise filaments. The first cut materialmay comprise a chromium cobalt alloy, the second cut material maycomprise nitinol, and the filaments may comprise nitinol. The first typeof material may comprise a cut material, the second type of material maycomprise the cut material, and the third type of material may comprisefilaments. The cut material may comprise nitinol and the filaments maycomprise nitinol. At least one of the first end portion, the second endportion, the intermediate portion, and the graft material may comprise abioabsorbable material. At least some of the graft material may beoutside the intermediate portion. At least some of the graft materialmay be inside the intermediate portion. At least some of the graftmaterial may be embedded within the intermediate portion. The device maybe capable of maintaining fluid flow between a first passage in whichthe first end portion is anchored and a second passage in which thesecond end portion is anchored. The first passage may be substantiallyparallel to the second passage. The intermediate portion may beconformable to an “S” shape.

In some implementations, a device comprises a first end portion, asecond end portion, an intermediate portion, and a graft material. Thefirst end portion comprises a first material. The second end portioncomprises a second material different than the first material. Theintermediate portion is between the first end portion and the second endportion. The graft material is coupled to at least the intermediateportion.

The first material may comprise nitinol and the second material maycomprise chromium cobalt. The first material may comprise nitinol andthe second material may comprise stainless steel. The first end portionmay comprise cut struts and the second end portion may comprisefilaments. The first end portion may comprise cut struts and the secondend portion may comprise cut struts. The first material may comprise analloy and the first end portion may comprise struts or filaments havinga first thickness, and the second material may comprise the alloy andthe second end potion may comprise struts or filaments having a secondthickness different than the first thickness. The intermediate portionmay comprise a third material. The third material may comprise nitinol.The intermediate portion may comprise filaments. The intermediateportion may comprise cut struts. At least one of the first end portionand the second end portion may be substantially cylindrical. At leastone of the first end portion, the second end portion, the intermediateportion, and the graft material may comprise a bioabsorbable material.At least some of the graft material may be outside the intermediateportion. At least some of the graft material may be inside theintermediate portion. At least some of the graft material may beembedded within the intermediate portion. The graft material may becoupled to at least one of the first end portion and the second endportion. The device may be capable of maintaining fluid flow between afirst passage in which the first end portion is anchored and a secondpassage in which the second end portion is anchored. The first passagemay be substantially parallel to the second passage. The intermediateportion may be conformable to an “S” shape.

In some implementations, a device comprises a support structure and agraft material. The support structure comprises a first end portion, asecond end portion, and an intermediate portion between the first endportion and the second end portion. At least one of the first endportion, the second end portion, and the intermediate portion comprisecut struts and at least one of the first end portion, the second endportion, and the intermediate portion comprise filaments. The graftmaterial is coupled to at least the intermediate portion.

The first end portion and the second end portion comprise cut struts andthe intermediate portion may comprise filaments. At least some of thegraft material may be outside the intermediate portion. At least some ofthe graft material may be inside the intermediate portion. At least someof the graft material may be embedded within the intermediate portion.The graft material may be coupled to at least one of the first endportion and the second end portion. The device may be capable ofmaintaining fluid flow between a first passage in which the first endportion is anchored and a second passage in which the second end portionis anchored. The first passage may be substantially parallel to thesecond passage. The intermediate portion may be conformable to an “S”shape.

The device may have a diameter between about 1 mm and about 12 mm (e.g.,between 2 mm and 6 mm). The device may have a diameter between about 1mm and about 10 mm (e.g., between 4 mm and 8 mm). The device may have adiameter between about 6 mm and about 25 mm (e.g., between 12 mm and 15mm). The device may have a diameter between about 20 mm and about 50 mm(e.g., between 35 mm and 40 mm). The device may have a length betweenabout 25 mm and about 150 mm (e.g., between 70 mm and 110 mm). Thedevice may include filaments having a diameter between about 0.001inches and about 0.01 inches (e.g., between 0.003 inches and 0.006inches). The device may include struts having a diameter between about0.001 inches and about 0.01 inches (e.g., between 0.003 inches and 0.006inches).

In some embodiments, a device for providing or maintaining fluid flowthrough at least one passage in a human or animal body includes two endportions for anchoring the device in position and an intermediateportion that allows movement of the end portions relative to eachanother. The end portions and the intermediate portion together define apathway for fluid flow through the device.

By allowing the two end portions to move relative to each other, thedevice can respond to movement of the passage or passages in which thedevice is used. The intermediate portion may be flexible to allowrelative movement of the end portions. In some embodiments, the devicehas varying or differential flexibility along the length of the deviceor along a length of a portion of the device. Device flexibility canreduce the likelihood of device failure due to fatigue, for examplebecause the magnitude of stresses within the intermediate portion may berelatively low in comparison to stresses on a support structure (e.g.,stent) with uniform flexibility along its entire length.

The device may be configured to provide or maintain fluid flow through asingle passageway, for example an occluded blood vessel. Theintermediate portion may be capable of maintaining fluid flow betweenproximal and distal portions of the occluded blood vessel. Theintermediate portion can pass through a further passage, for exampleoutside the blood vessel, extending between the proximal and distalportions of the blood vessel. The device may be configured for use as abypass between proximal and distal portions of a single blood vessel,for example an artery or a vein.

The device may be configured to provide fluid flow from an occludedblood passage to another passage. The passages can be interconnected bythe intermediate portion passing through a further passage extendingbetween the two passages. The device may be configured for use as ashunt between two passages, for example between an artery and a vein.

In embodiments in which the end portions can move relative to oneanother by virtue of the intermediate portion, the device may besuitable for use in applications where the end portions are anchored inseparate passages that move relative to one another. A pathway for fluidcommunication to be maintained through the device irrespective of therelative movement of the end portions, and the likelihood of fatiguefailure of the device due to cyclic movement of the end portions may below in comparison to a support structure (e.g., stent) lacking such anintermediate portion.

One or both of the end portions may be diametrically expandable toanchor the device in position. An expanded end portion may, for example,be expandable to meet with and press against the inner sidewalls of apassage to inhibit or prevent substantial sliding or rotation of the endportion within the passage, and/or to dilate the passage. Theintermediate portion may be diametrically expandable, for example todilate the fluid flow pathway.

The device may be in the form of a tube defining a lumen configured toact as a fluid flow pathway. In some embodiments, the tube may befluid-tight, so as to confine the fluid flow within the lumen of thetube. The tube may include, but is not limited to, a polymeric material,for example a biocompatible polymer such as polytetrafluoroethylene(PTFE) or polyurethane such as polycarbonate aromatic biodurablethermoplastic polyurethane elastomer (e.g., ChronoFlex C® 80A and 55Dmedical grade, available from AdvanSource Biomaterials of Wilmington,Mass.).

The device may include a supporting structure that supports the endportions. The supporting structure may support the intermediate portion,in which case the supporting structure may be flexible within theintermediate portion to allow movement of the end portions relative toeach other.

When a supporting structure is provided, the supporting structure or aportion thereof may be embedded within a wall of the tube. Alternativelyor in addition, the structure or a portion of the structure may belocated on the outside of the tube or within the lumen of the tube.

The supporting structure may include at least one mesh. For example, asingle mesh may extend along the entire length of the device. In anotherexample, each end of the device includes a mesh, in which case themeshes may stop short of the intermediate portion or may extend into theintermediate portion. When a mesh is present in the intermediateportion, the mesh may have a higher density or smaller window size(e.g., a smaller spacing between filaments and/or struts of the mesh) inthe end portions than in the intermediate portion so that the device isrelatively more flexible in the intermediate portion than in the endportions. The device may be relatively more flexible in the intermediateportion than in the end portions by way of absence of a mesh, or evenwhen including a mesh with substantially uniform or uniform density orwindow size (e.g., due to factors other than mesh density or windowsize), or by including a mesh having a non-uniform density.

At least one mesh may include biocompatible metal wire. For example, themetal wire may be stainless steel. Alternatively, or in addition, atleast one mesh may include a shape memory material, for example nitinoland/or chromium cobalt. When a shape memory material is used, at least aportion of the device may be self-expanding.

One or both end portions may include anchoring protuberances or barbscapable of and/or configured to dig into or grasp the inside sidewallsof a passage, for example to prevent or reduce slippage or othermovement of the or each end portion relative to the passage.

The two end portions may have different diameters, so that the devicecan be made to fit securely within a passage having variable diameter,or with one end portion in a first passage and the other end portion ina second passage, when the passages have different diameters. The devicecan be configured for a particular application and/or for a particularpatient.

In some embodiments, a method of diverting fluid flow from a firstpassage to a second passage (e.g., adjacent to the first passage)includes forming a third passage between the first and second passages,providing a device having two end portions and an intermediate portion,deforming the intermediate portion of the device to permit insertion ofthe device in the passages, and expanding the end portions against thewalls of the first and second passages so as to anchor the device in thepassages. The intermediate portion of the device may be flexed to permitinsertion of the device in the passages. The two end portions and theintermediate portion may be configured to maintain or provide fluid flowthrough the device.

One or more end portions of the device may be expanded by a ballooncatheter. Alternatively, or in addition, at least one end portion may beself-expanding, in which case the method may include providing thedevice in a retaining sleeve, and removing the retaining sleeve toenable the at least one end portion to expand.

The method may further include expanding the intermediate portion todilate the third passage, thereby forming a larger pathway for fluidflow from the first passage to the second passage.

The methods described herein may be used in many surgical procedures,and can be performed by minimally invasive (key-hole) techniques. Themethods may be particularly suitable for the treatment of coronary heartdisease, for example by providing a shunt or bypass to divert arterialblood from an occluded coronary artery to a coronary vein (e.g.,adjacent to the coronary artery) and/or by traversing an occlusion in acoronary artery by exiting the artery proximal to the occlusion,extending through subintimal tissue, external tissue, and/or a portionof a proximate vessel, and reentering the coronary artery distal to theocclusion, for peripheral vascular disease such as critical limbischemia, for example by providing a shunt or bypass to divert arterialblood from an occluded peripheral artery to a peripheral vein and/or bytraversing an occlusion in a peripheral vessel by exiting the vesselproximal to the occlusion, extending through subintimal tissue, externaltissue, and/or a portion of a proximate vessel, and reentering thevessel distal to the occlusion, and/or for non-occluded vessels, forexample by creating a shunt between a healthy artery and a healthy veinthat can be used for dialysis access.

In some embodiments, a method of treating coronary heart diseaseincludes diverting arterial blood from a coronary artery to a coronaryvein by the methods described herein. In some embodiments, a method oftreating critical limb ischemia includes diverting arterial blood from aperipheral artery to a peripheral vein by the methods described herein.

For purposes of summarizing the invention and the advantages that may beachieved, certain objects and advantages are described herein. Notnecessarily all such objects or advantages need to be achieved inaccordance with any particular embodiment. In some embodiments, theinvention may be embodied or carried out in a manner that can achieve oroptimize one advantage or a group of advantages without necessarilyachieving other objects or advantages.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will be apparentfrom the following detailed description having reference to the attachedfigures, the invention not being limited to any particular disclosedembodiment(s). Optional and/or preferred features described withreference to some embodiments may be combined with and incorporated intoother embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention, in which like reference numerals are usedfor like features, and in which:

FIG. 1 is a side perspective view of an example embodiment of a devicefor providing fluid flow;

FIG. 2 shows the device of FIG. 1 in use as a shunt between two bloodvessels;

FIG. 3 is a side perspective view of another example embodiment of adevice for providing fluid flow; and

FIG. 4 is a side perspective view of still another example embodiment ofa device for providing fluid flow.

FIG. 5 is a side perspective view of yet another example embodiment of adevice for providing fluid flow.

FIG. 6 is a side perspective view of yet still another exampleembodiment of a device for providing fluid flow.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, theinvention extends beyond the specifically disclosed embodiments and/oruses and obvious modifications and equivalents thereof. The scope of theinvention herein disclosed should not be limited by any particularembodiments described below.

The present application describes devices and methods usable inminimally invasive surgical procedures, which can reduce performance ofconventional surgery to treat conditions such as coronary heart diseaseand critical limb ischemia. For example, patients who might otherwise beunable to receive surgery such as coronary bypass surgery or peripheralarterial bypass surgery can be treated, and the amount of surgicaltrauma, the risk of infection, and/or the time to recovery may bereduced or significantly reduced in comparison to conventional surgery.

Some methods and devices for performing procedures such as coronarybypass and peripheral arterial bypass by minimally invasive surgicaltechniques are described in International Patent Application No.PCT/GB05/003480 (Publication No. WO 2006/027599), entitled “MinimallyInvasive Surgical Apparatus and Methods,” the contents of which arehereby incorporated into this specification by reference in theirentirety, in particular techniques for effectively bypassing anocclusion in an artery by percutaneous surgery. These techniques includecreating a channel or passage between a first passage, such as an arteryupstream of an occlusion, a vein, or a heart chamber, and a secondpassage, such as an artery, vein, or heart chamber, proximate to thefirst passage to interconnect the first and second passages by a thirdpassage. Fluid such as blood may be diverted from the first passage intothe second passage by way of the interconnecting third passage. Inembodiments in which the first passage includes an artery and the secondpassage includes a vein, the arterial blood can perfuse into tissue in aretrograde manner (retroperfusion).

The interconnecting passage between the first and second passages can becreated by, for example, deploying a needle outwards from a firstcatheter located within the first passage, so that the needle traversesthe interstitial tissue or septum between the first and second passages.A second catheter may be located in the second passage, so as to providea target device which receives a signal, for example an ultrasoundsignal, transmitted from the first catheter. By monitoring the receivedsignal, the position of the first catheter with respect to the secondcatheter can be determined so as to ensure that the needle is deployedin the correct position and orientation to create a passage for fluidflow between the first and second passages.

In order to provide or maintain the flow of blood thorough theinterconnecting passage or channel, a structure including a lumen may beinserted in the passage to support the interstitial tissue and/or toinhibit or prevent the passage from closing. The tube may, for example,include a stent expanded in the channel using a balloon catheter orself-expansion, as described herein. A catheter to deliver thestructure, for example a balloon catheter or catheter that allowsself-expansion, may be guided to the channel by a guide wire deployed inthe passage by the first catheter.

Passages such as arteries, veins, and heart chambers can pulsate as theheart beats, for example due to movement of heart walls, peripherallimbs, and/or fluctuations in pressure within the passages themselves.This pulsation can cause movement of the passages relative to eachanother, which can impose stress on a structure within aninterconnecting passage therebetween. This stress may be large incomparison to stress experienced by a structure within a single passage.Stress can lead to premature failure of the structure, for example byfatigue failure of the stent struts. Failure of the structure may resultin injury to the interstitial tissue and/or occlusion of theinterconnecting passage, which could lead to significant complicationsor complete failure of the therapy.

FIG. 1 illustrates a device or implant or prosthetic 10 for providing ormaintaining fluid flow through at least one passage. The device 10includes a first or proximal end portion 12, a second or distal endportion 14, and an intermediate portion 16 between the proximal endportion 12 and the distal end portion 14. The device includes a bore orlumen 20 for passage of fluid through the device 10. The device 10, forexample at least the intermediate portion 16 of the device 10, includesa flexible polymer tube 18. The flexible polymer tube 18 may at leastpartially define the lumen 20.

The device 10 includes a support structure (e.g., at least one stent)including a mesh 22 and a mesh 24. In some embodiments, at least aportion of the mesh 22 is embedded in the outside wall of the tube 18proximate to the proximal end portion 12 of the device 10. In someembodiments, at least a portion of the mesh 24, for example a wire or astrut, is embedded in the outside wall of the tube 18 proximate to thedistal end portion 14 of the device 10. The meshes 22, 24 may includebiocompatible metal such as stainless steel and/or shape memory materialsuch as nitinol or chromium cobalt.

The wire meshes 22, 24 can stiffen the end portions 12, 14,respectively. In some embodiments in which the intermediate portion 16does not include a mesh, the intermediate portion 16 may be relativelyflexible in comparison to the end portions 12, 14, and/or the endportions 12, 14 may have a relatively high radial stiffness.

In some embodiments, the end portions 12, 14 of the device 10 arediametrically expandable. For example, the wire meshes 22, 24 may have asmaller diameter after formation or manufacture than the passages, forexample blood vessels, into which the device 10 will be deployed. Whenthe device 10 is in position in the passages, the end portions 12, 14can be expanded or deformed outwardly so that the respective diametersof the end portions 12, 14 increase, for example to abut the interiorsidewalls of the passages. The end portions 12, 14 are configured tomaintain the expanded diameter indefinitely, for example by plasticdeformation of the material (e.g., wires, struts) of the meshes 22, 24and/or by provision of a locking mechanism arranged to mechanically lockthe meshes 22, 24 in the expanded position. The intermediate portion 16of the device 10 may be diametrically expandable, for example by way ofplastic deformation of the tube 18.

FIG. 2 shows the device 10 of FIG. 1 deployed to provide a fluid flowpath between a first passage 26 and a second passage 28. The passages26, 28 may include coronary blood vessels, for example a coronary artery26 and a coronary vein 28, or vice versa. The passages 26, 28 mayinclude peripheral blood vessels (e.g., blood vessels in limbs), forexample a femoral or other peripheral artery 26 and a femoral or otherperipheral vein 28, or vice versa. The end portions 12, 14 and theintermediate portion 16 of the device 10 have been expanded to meet withand push against the inner walls of the passages 26, 28. The distal endportion 14 of the device 10 is located within the second passage 28, andthe proximal end portion 12 of the device 10 is located within the firstpassage 26. The intermediate portion 16 extends through an opening orinterconnecting passage 30 surgically formed between the passages 26,28.

The expanded end portions 12, 14 of the device 10 are resilient, andimpart an outward radial force on the inner walls of the passages 26,28. By virtue of the radial stiffness of the end portions 12, 14 of thedevice 10, the end portions 12, 14 are held or anchored in place withinthe respective passages 26, 28. Slippage of the device 10 within thepassages 26, 28 is thereby prevented or reduced. In this way, the endportions 12, 14 of the device 10 can anchor or fix the device 10 inposition, in use, while providing or maintaining fluid flow through thelumen 20 of the tube 18 (FIG. 1). In this way, the device 10 can act asa shunt between the first passage 26 and the second passage 28.

The intermediate portion 16 of the device 10 may be flexible, forexample allowing the intermediate portion 16 to form an ‘S’ shape formedby the combination of the first passage 26, the second passage 28, andthe interconnecting passage 30 (FIG. 2). The flexible intermediateportion 16 can allow the end portions 12, 14 of the device 10 to movewith respect to one another in response to relative movement of thepassages 26, 28.

In embodiments in which the intermediate portion 16 does not include awire mesh but includes the flexible polymer material of the tube 18, theintermediate portion 16 may not be susceptible to damage due to meshfatigue, for example upon cyclic or other stress imparted by relativemovement of the passages 26, 28.

The intermediate portion 16 of the device 10 has sufficient resilienceto maintain dilatation of the interconnecting passage 30, so that theinterconnecting passage 30 remains open to provide or maintain a pathfor blood flow from the artery 26 to the vein 28 by way of the lumen 20of the tube 18 (FIG. 1). Blood flow from the artery 26 to the vein 28,by way of the interconnecting passage 30, may thereby be provided ormaintained through the lumen 20 of the tube 18. The device 10 at leastpartially supports the artery 26, the vein 28, and the interconnectingpassage 30 to provide a pathway for fluid communication through thedevice 10.

The proximal end portion 12 and the distal end portion 14 of the device10 are arranged so that, when the device 10 is deployed with the distalend portion 14 in a vein 28 and the proximal end portion 12 in an artery26, for example as shown in FIG. 2, the diameter of the expanded distalend portion 14 is sufficient to hold the distal end portion 14 withinthe vein 28, and the diameter of the expanded proximal end portion 12 issufficient to hold the proximal end portion 12 within the artery 26. Thediameter of the proximal end portion 12 may therefore differ from thediameter of the distal end portion 14. By selecting appropriatediameters for the end portions 12, 14 and the intermediate portion 16,the device 10 can be tailored to a certain anatomy and/or the anatomy ofan individual patient.

An example procedure for positioning the device 10 of FIG. 1 to providea shunt between an occluded artery 26 and a vein 28 (e.g., a coronaryartery 26 and a coronary vein 28, or a peripheral artery 26 and aperipheral vein 28) to achieve retroperfusion of arterial blood, forexample as shown in FIG. 2, will now be described.

A catheter may be inserted into the patient's arterial system by way ofa small aperture cut, usually in the patient's groin area. The catheteris fed to the artery 26 and guided to a position upstream of the site ofthe occlusion, for example at a site proximate and parallel orsubstantially parallel to a vein 28. A hollow needle is deployed fromthe catheter, through the wall of the artery 26, through theinterstitial tissue 32 that separates the artery 26 and vein 28, andthrough the wall of the vein 28. The path of the needle creates aninterconnecting passage or opening 30, which allows blood to flowbetween the artery 26 and the vein 28. Deployment of the needle may beguided by a transmitter (e.g., a directional ultrasound transmitter)coupled to a catheter in the artery 26 and a receiver (e.g., anomnidirectional ultrasound receiver) coupled to a catheter in the vein28, or vice versa, for example as described in International PatentApplication No. PCT/GB05/003480. Other methods of forming the opening 30are also possible (e.g., with or without guidance, from vein to artery,etc.).

Before the needle is withdrawn from the passage 30, a guide wire isinserted through the hollow needle and into the vein 28. The needle isthen retracted, leaving the guide wire in place in the artery 26, thepassage 30, and the vein 28. The catheter carrying the needle can thenbe withdrawn from the patient's body. The guide wire can be used toguide further catheters to the interconnecting passage 30 between theartery 26 and the vein 28.

A catheter carrying the device 10 in a non-expanded state is advancedtowards the interconnecting passage 30, guided by the guide wire, forexample by a rapid exchange lumen or through the lumen 20. The cathetermay include, for example, a balloon catheter configured to expand atleast a portion of the device 10 and/or a catheter configured to allowself-expansion of at least a portion of the device 10. The distal endportion 14 of the device 10 is passed through the interconnectingpassage 30 and into the vein 28, leaving the proximal end portion 12 inthe artery 26. The intermediate portion 16 of the device 10 is at leastpartially in the passage 30, and is at least partially within the artery26 and the vein 28. The intermediate portion 16 flexes to adopt a curvedor “S”-shaped formation, depending on the anatomy of the site. Adoptionof such curvature may conform the shape of an intermediate portion 16extending through the interconnecting passage 30, and optionally into atleast one of the passages 26, 28, to the shape of at least theinterconnecting passage 30.

The distal end portion 14 of the device 10 is expanded, for example uponinflation of a balloon or by self-expansion, so as to increase thediameter of the distal end portion 14 and anchor the distal end portion14 against the inner wall of the vein 28. The catheter may be adapted toexpand the intermediate portion 16 of the device 10, for example byinflation of a balloon, so that the interconnecting passage 30 can bewidened or dilated to obtain blood flow (e.g., sufficient blood flow)from the artery 26 to the vein 28. The proximal end portion 12 of thedevice 10 is expanded, for example upon inflation of a balloon or byself-expansion, so as to increase the diameter of the proximal endportion 12 and anchor the proximal end portion 12 against the inner wallof the artery 26.

After the end portions 12, 14 of the device 10 are expanded, for exampledue to self-expansion and/or balloon expansion, and with or withoutimproving expansion after deployment, the catheter and the guide wireare withdrawn from the patient's body. In this way, the device 10 isanchored or fixed in position within the vein 28, the artery 26, and theinterconnecting passage 30 as shown in FIG. 2.

The catheter may be adapted to selectively expand the proximal endportion 12, the distal end portion 14, and/or the intermediate portion16 of the device 10 individually or in combination, for example by theprovision of two or more separately inflatable balloons or balloonportions, a single balloon configured to expand all of the portions ofthe device 10 simultaneously, or a single balloon configured to expandone or more selected portions of the device 10. For example, the endportions 12, 14 may be self-expanding, and the intermediate portion 16may be expanded by a balloon to dilate the passage 30. In someembodiments including balloon expansion, all or selected parts of thedevice 10 may be expanded, for example, simultaneously by a balloonacross the entire length of the device 10 or by a plurality of balloonslongitudinally spaced to selectively inflate selected parts of thedevice 10, and/or sequentially by a balloon or plurality of balloons. Insome embodiments including at least partial self-expansion, all orselected parts of the device 10 may be expanded, for example, byproximal retraction of a sheath over or around the device 10, which canlead to deployment of the device 10 from distal to proximal as thesheath is proximally retracted. Deployment of the device 10 proximal todistal and deployment of the device 10 intermediate first then the endsare also possible.

Other steps may be included in the procedure. For example, before thedevice 10 is deployed, a balloon catheter may be guided to theinterconnecting passage 30 and positioned so that an inflatable balloonportion of the catheter lies in the interconnecting passage 30. Uponinflation of the balloon, the balloon pushes against the walls of theinterconnecting passage 30 to widen or dilate the interconnectingpassage 30 to ease subsequent insertion of the device 10.

FIG. 3 illustrates another device 34 for providing fluid flow through atleast one passage. The device 34 includes a mesh 36 and a polymer tube18. The mesh 36 is shown as being on the outside of the polymer tube 18,but as described herein could also or alternatively be on an inside ofthe polymer tube and/or within the polymer tube 18. As described withrespect to the device 10, the device 34 includes a proximal end portion12, a distal end portion 14, and an intermediate portion 16. In theembodiment illustrated in FIG. 3, the mesh 36 extends along the entirelength of the device 34, including along the intermediate portion 16.

In some embodiments, the spacing of filaments or struts of the mesh 36varies along the length of the device 34. For example, winding densityof a woven or layered filamentary mesh may be varied and/or a windowsize pattern of a cut mesh may be varied.

In some embodiments, the spacing may be relatively small in the proximalend portion 12 and the distal end portions 14, and the spacing may berelatively large in the intermediate portion 16. In other words, thedensity or window size of the mesh 36 may be relatively low in theintermediate portion 16, and the density or window size of the mesh 36may be relatively high in the end portions 12, 14. In certain suchembodiments, the intermediate portion 16 may be flexible in comparisonto the end portions 12, 14. The relatively rigid end portions 12, 14 mayengage and anchor in passages. Although the mesh 36 in the intermediateportion 16 may be subject to stress such as cyclic stress, in use, therelatively high flexibility of the intermediate portion 16 due to thelow density or window size allows the impact of the stress to be lowbecause the intermediate portion 16 can flex in response to the stress.The risk of fatigue failure of the device 34, and particularly thefilaments or struts 38 of the mesh 36, may therefore be reduced incomparison to a device having uniform flexibility along its entirelength.

In some embodiments, the spacing may be relatively large in the proximalend portion 12 and the distal end portions 14, and the spacing may berelatively small in the intermediate portion 16. In other words, thedensity of the mesh 36 may be relatively high (or the window size of themesh 36 may be relatively low) in the intermediate portion 16, and thedensity of the mesh 36 may be relatively low (or the window size of themesh 36 may be relatively high) in the end portions 12, 14. In certainsuch embodiments, the intermediate portion 16 may have radial strengthsufficient to inhibit or prevent collapse of the passage 30, yet still,flexible enough to flex in response to stress such as cyclic stress. Theend portions 12, 14 may engage and anchor in passages.

FIG. 4 illustrates another device or implant or prosthetic 40 forproviding fluid flow through at least one passage. As described withrespect to the device 10, the device 40 includes a proximal end portion12, a distal end portion 14, and an intermediate portion 16. The device40 includes a polymer tube 18 and a support structure including a firstmesh 42 and a second mesh 44. The first mesh 42 extends from theproximal end portion 12 toward (e.g., into) the intermediate portion 16and optionally into the distal end portion 14. The second mesh 44extends from the distal end portion 14 toward (e.g., into) theintermediate portion 16 and optionally into the proximal end portion 12.The meshes 42, 44 thereby overlap each other at least in theintermediate portion 16. Both meshes 42, 44 may be on the outside of thetube 18, on the inside of the tube 18, or embedded within the tube 18,or one mesh may be on the outside of the tube 18, on the inside of thetube 18, or embedded within the tube 18 while the other mesh isdifferently on the outside of the tube 18, on the inside of the tube 18,or embedded within the tube 18 (e.g., one mesh inside the tube 18 andone mesh outside the tube 18). The meshes 42, 44 may be formed, forexample, by winding wire in a lattice configuration around or inside thepolymer tube 18, by placing a cut tube around or inside the polymer tube18, by being embedded in the polymer tube 18, combinations thereof, andthe like.

In some embodiments, the density of the meshes 42, 44 is relatively high(or the window size of the meshes 42, 44 is relatively low) in theirrespective end portions 12, 14 and decreases in density (or increases inwindow size) towards the intermediate portion 16. The total windingdensity (e.g., the winding density of both meshes 42, 44, takentogether) may be lower in the intermediate portion 16 than in the endportions 12, 14, or the total window size (e.g., the window size of bothmeshes 42, 44, taken together) may be higher in the intermediate portion16 than in the end portions 12, 14. In certain such embodiments, theintermediate portion 16 is relatively flexible in comparison to the endportions 12, 14. In some embodiments, the meshes 42, 44 do not extendinto the intermediate portion, and absence of a mesh could cause theintermediate portion 16 to be relatively flexible in comparison to theend portions 12, 14. In some embodiments, as window size increases(e.g., longitudinally along a tapered portion of the device 40), thedensity decreases, the mesh coverage decreases, and/or the porosityincreases because the width of the struts and/or filaments remainssubstantially constant or constant or does not increase in the sameproportion as the window size, which could provide a change inflexibility along a longitudinal length.

The first and second meshes 42, 44 may include different materials,which can allow optimization of the properties of each of the respectivedistal and proximal end portions 12, 14 of the device 40 for aparticular application of the device 40. For example, the second mesh 44at the distal end portion 14 of the device 40 may include a relativelyflexible metallic alloy for ease of insertion through an interconnectingpassage between two blood vessels, while the first mesh 42 at theproximal end portion 12 of the device 40 may include a relativelyinelastic metallic alloy to provide a high degree of resilience at theproximal end portion 14 to anchor the device 40 firmly in position. Thefirst and second meshes 42, 44 could include the same materialcomposition (e.g., both including nitinol) but different wire diameters(gauge) or strut thicknesses.

FIG. 5 illustrates another device or implant or prosthetic 50 forproviding fluid flow through at least one passage. The device 50includes a support structure (e.g., stent) 56 and a graft 58. Asdescribed with respect to the device 10, the device 50 includes aproximal end portion 12, a distal end portion 14, and an intermediateportion 16. The proximal end portion 12 includes a cylindrical orsubstantially cylindrical portion and the distal end portion 14 includesa cylindrical or substantially cylindrical portion. The diameter of theproximal end portion 12 is smaller than the diameter of the distal endportion 14. In some embodiments, the diameter of the proximal endportion 12 is larger than the diameter of the distal end portion 14. Theintermediate portion 16 has a tapered or frustoconical shape between theproximal end portion 12 and the distal end portion 14. The stent 56 mayinclude filaments (e.g., woven, layered), a cut tube or sheet, and/orcombinations thereof.

Parameters of the stent 56 may be uniform or substantially uniformacross a portion and/or across multiple portions, or may vary within aportion and/or across multiple portions. For example, the stent 56 atthe proximal end portion 12 may include a cut tube or sheet, the stent56 at the distal end portion 12 may include a cut tube or sheet, and thestent 56 at the intermediate portion 16 may include filaments (e.g.,woven or layered). Certain such embodiments may provide good anchoringby the proximal end portion 12 and the distal end portion 14 and goodflexibility (e.g., adaptability to third passage sizes and dynamicstresses) of the intermediate portion 16.

The stent 56 may include different materials in different portions. Forexample, the stent 56 at the proximal end portion 12 may includechromium cobalt and/or tantalum, the stent 56 at the distal end portion14 may include nitinol, and the stent 56 at the intermediate portion 16may include nitinol. Certain such embodiments may provide good anchoringand/or wall apposition by the device 50 in each deployment areas (e.g.,the proximal end portion 12 engaging sidewalls of an artery, the distalend portion 14 engaging sidewalls of a vein, and the intermediateportion 16 engaging sidewalls of the passage between the artery and thevein).

Combinations of support structure materials and types are also possible.For example, the stent 56 at the proximal portion may include a cut tubeor sheet including chromium cobalt and/or tantalum, the stent 56 at thedistal end portion 14 may include a cut tube or sheet including nitinol,and the stent 56 at the intermediate portion 16 may include filamentsincluding nitinol.

In embodiments in which the stent 56 includes at least one portionincluding a cut tube or sheet, the cut pattern may be the same. Forexample, the cut pattern may be the same in the proximal end portion 12and the distal end portion 14, but proportional to the change indiameter. In some embodiments, the window size or strut density isuniform or substantially uniform within a portion 12, 14, 16, within twoor more of the portions 12, 14, 16, and/or from one end of the stent 56to the other end of the stent 56. In embodiments in which the stent 56includes at least one portion including filaments, the winding may bethe same. For example, the winding may be the same in the proximal endportion 12 and the distal end portion 14, but changed due to the changein diameter. In some embodiments, the winding density or porosity isuniform or substantially uniform within a portion 12, 14, 16, within twoor more of the portions 12, 14, 16, and/or from one end of the stent 56to the other end of the stent 56. In embodiments in which the stent 56includes at least one portion including a cut tube or sheet and at leastone portion including filaments, the cut pattern and winding may beconfigured to result in a uniform or substantially uniform density.Non-uniformity is also possible, for example as described herein.

The graft 58 may include materials and attachment to the stent 56 asdescribed with respect to the tube 18. The graft 58 generally forms afluid-tight passage for at least a portion of the device 50. Althoughillustrated as only being around the intermediate portion 16, the graft58 may extend the entire length of the device 50, or may partiallyoverlap into at least one of the cylindrical end portions 12, 14.

FIG. 6 illustrates another device 60 for providing fluid flow through atleast one passage. The device 60 includes a support structure (e.g.,stent) and a graft 68. As described with respect to the device 10, thedevice 60 includes a proximal end portion 12, a distal end portion 14,and an intermediate portion 16. The proximal end portion 12 includes atapered or frustoconical portion and the distal end portion 14 includesa tapered or frustoconical portion. The diameter of the proximal end ofthe proximal end portion 12 is smaller than the diameter of the distalend of the distal end portion 14. In some embodiments, the diameter ofthe proximal end of the proximal end portion 12 is larger than thediameter of the distal end of the distal end portion 14. Theintermediate portion 16 has a tapered or frustoconical shape between theproximal end portion 12 and the distal end portion 14. In someembodiments, the angle of inclination of the portions 12, 14, 16 is thesame or substantially the same (e.g., as illustrated in FIG. 6). In someembodiments, the angle of inclination of at least one portion is sharperor narrower than at least one other portion. The frustoconical proximalend portion 12 and distal end portion 14 may allow better anchoring in abody passage, for example because arteries tend to taper with distancefrom the heart and veins tend to taper with distance towards the heart,and the end portions 12, 14 can be configured to at least partiallycorrespond to such anatomical taper.

As described above with respect to the support structure 56, the supportstructure 66 may include filaments (e.g., woven, layered), a cut tube orsheet, the same materials, different materials, and combinationsthereof.

The graft 68 may include materials and attachment to the stent 66 asdescribed with respect to the tube 18. The graft 68 generally forms afluid-tight passage for at least a portion of the device 60. Althoughillustrated as only being around the intermediate portion 16, the graft68 may extend the entire length of the device 60, or may partiallyoverlap into at least one of the frustoconical end portions 12, 14.

In some embodiments, a combination of the device 50 and the device 60are possible. For example, the proximal end portion 12 can becylindrical or substantially cylindrical (e.g., as in the device 50),the distal end portion 14 can be tapered or frustoconical (e.g., as inthe device 60), with the proximal end portion 12 having a largerdiameter than the distal end of the distal end portion 14. For anotherexample, the proximal end portion 12 can be tapered or frustoconical(e.g., as in the device 60), the distal end portion 14 can becylindrical or substantially cylindrical (e.g., as in the device 50),with the proximal end of the proximal end portion 12 having a largerdiameter than the distal end portion 14. In each example, theintermediate portion 16 can have a tapered or frustoconical shapebetween the proximal end portion 12 and the distal end portion 14.

An example deployment device for the implantable devices describedherein is described in U.S. patent application Ser. No. 12/545,982,filed Aug. 24, 2009, and U.S. patent application Ser. No. 13/486,249,filed Jun. 1, 2012, the entire contents of each of which is herebyincorporated by reference. The device generally includes a handle at theproximal end with a trigger actuatable by a user and a combination oftubular member at the distal end configured to be pushed and/or pulledupon actuation of the trigger to release the device. Other deliverydevices are also possible. The delivery device may include a portionslidable over a guide wire (e.g., a guide wire that has been navigatedbetween the artery and the vein via a tissue traversing needle) and/ormay be trackable through a lumen of a catheter.

Although certain embodiments and examples are shown or described hereinin detail, various combinations, sub-combinations, modifications,variations, substitutions, and omissions of the specific features andaspects of those embodiments are possible, some of which will now bedescribed by way of example only.

The device, for example a stent of the device, a mesh of the device, asupport structure of the device, etc., may be self-expanding. Forexample, a mesh may include a shape-memory material, such as nitinol,which is capable of returning to a pre-set shape after undergoingdeformation. In some embodiments, the stent may be manufactured to ashape that is desired in the expanded configuration, and is compressibleto fit inside a sleeve for transport on a catheter to a vascular site.To deploy and expand the stent, the sleeve is drawn back from the stentto allow the shape memory material to return to the pre-set shape, whichcan anchor the stent in the passages, and which may dilate the passagesif the stent has sufficient radial strength. The use of a ballooncatheter is not required to expand a fully self-expanding stent, but maybe used, for example, to improve or optimize the deployment.

A device may include one or more self-expanding portions, and one ormore portions which are expandable by deformation, for example using aballoon catheter. For example, in the embodiment shown in FIG. 4, thefirst mesh 42 may include stainless steel expandable by a ballooncatheter, and the second mesh 44 may include nitinol for self-expansionupon deployment.

With respect to any of the embodiments described herein, the polymertube 18, including the grafts 58, 68, may include any suitable compliantor flexible polymer, such as PTFE, silicone, polyethylene terephthalate(PET), polyurethane such as polycarbonate aromatic biodurablethermoplastic polyurethane elastomer (e.g., ChronoFlex C® 80A and 55Dmedical grade, available from AdvanSource Biomaterials of Wilmington,Mass.), combinations thereof, and the like. The polymer tube 18 mayinclude biodegradable, bioabsorbable, or biocompatible polymer (e.g.,polylactic acid (PLA), polyglycolic acid (PGA), polyglycolic-lactic acid(PLGA), polycaprolactone (PCL), polyorthoesters, polyanhydrides,combinations thereof, etc. The polymer may be in tube form beforeinteraction with a support structure (e.g., stent), or may be formed on,in, and/or around a support structure (e.g., stent). For example, thepolymer may include spun fibers, a dip-coating, combinations thereof,and the like. In some embodiments, for example when the device is to bedeployed within a single blood vessel, the device may omit the tube. Incertain such embodiments, the intermediate portion of the stent mayinclude a mesh with a low winding density or high window size, while theend portions of the stent include a mesh with a higher winding densityor lower window size, the mesh being generally tubular to define apathway for fluid flow through the center of the mesh. In someembodiments, the polymer tube 18 includes a lip (e.g., comprising thesame or different material), which can help form a fluid-tight sealbetween the polymer tube 18 and the body passages. The seal may beangled, for example to account for angled positioning of the polymertube 18 between body passages. In some embodiments, the polymer tube 18may extend longitudinally beyond the support structure in at least onedirection, and the part extending beyond is not supported by the supportstructure.

The mesh may include any suitable material, such as nickel, titanium,chromium, cobalt, tantalum, platinum, tungsten, iron, manganese,molybdenum, combinations thereof (e.g., nitinol, chromium cobalt,stainless steel), and the like. The mesh may include biodegradable,bioabsorbable, or biocompatible polymer (e.g., polylactic acid (PLA),polyglycolic acid (PGA), polyglycolic-lactic acid (PLGA),polycaprolactone (PCL), polyorthoesters, polyanhydrides, combinationsthereof, etc.) and/or glass, and may lack metal. Different materials maybe used for portions of the mesh or within the same mesh, for example aspreviously described with reference to FIG. 4. For example, the mesh 24at the distal end portion 14 and the mesh 22 at the proximal end portion12 of the device 10 may include different materials. For anotherexample, the mesh 22, and/or the mesh 24, may include a metallic alloy(e.g., comprising cobalt, chromium, nickel, titanium, combinationsthereof, and the like) in combination with a different type of metallicalloy (e.g., a shape memory alloy in combination with a non-shape memoryalloy, a first shape memory alloy in combination with a second shapememory alloy different than the first shape memory alloy, a cladmaterial (e.g., comprising a core including a radiopaque material suchas titanium, tantalum, rhenium, bismuth, silver, gold, platinum,iridium, tungsten, etc.)) and/or a non -metallic material such as apolymer (e.g., polyester fiber), carbon, and/or bioabsorbable glassfiber. In some embodiments, at least one mesh 22, 24 comprises nitinoland stainless steel. The nitinol may allow some self-expansion (e.g.,partial and/or full self-expansion), and the mesh could then be furtherexpanded, for example using a balloon.

Although generally illustrated in FIGS. 1, 3, and 4 as a woven filamentmesh, any other structure that can provide the desired degree ofresilience may be used. For example, layers of filaments wound inopposite directions may be fused at the filament ends to provide anexpandable structure. For another example, a metal sheet may be cut(e.g., laser cut, chemically etched, plasma cut, etc.) to formperforations and then heat set in a tubular formation or a metal tube(e.g., hypotube) may be cut (e.g., laser cut, chemically etched, plasmacut, etc.) to form perforations. A cut tube (including a cut sheetrolled into a tube) may be heat set to impart an expanded configuration.

Filaments or wires or ribbons that may be woven or braided, or layeredor otherwise arranged, are generally elongate and have a circular, oval,square, rectangular, etc. transverse cross-section. Example non-wovenfilaments can include a first layer of filaments wound in a firstdirection and a second layer of filaments wound in a second direction,at least some of the filament ends being coupled together (e.g., bybeing coupled to an expandable ring). Example braid patterns includeone-over-one-under-one, a one-over-two-under-two, atwo-over-two-under-two, and/or combinations thereof, although otherbraid patterns are also possible. At filament crossings, filaments maybe helically wrapped, cross in sliding relation, and/or combinationsthereof. Filaments may be loose (e.g., held together by the weave)and/or include welds, coupling elements such as sleeves, and/orcombinations thereof. Ends of filaments can be bent back, crimped (e.g.,end crimp with a radiopaque material such as titanium, tantalum,rhenium, bismuth, silver, gold, platinum, iridium, tungsten, etc. thatcan also act as a radiopaque marker), twisted, ball welded, coupled to aring, combinations thereof, and the like. Weave ends may includefilament ends and/or bent-back filaments, and may include open cells,fixed or unfixed filaments, welds, adhesives, or other means of fusion,radiopaque markers, combinations thereof, and the like. Parameters ofthe filaments may be uniform or substantially uniform across a portionand/or across multiple portions, or may vary within a portion and/oracross multiple portions. For example, the proximal end portion 12 mayinclude a first parameter and the distal end portion 14 may include asecond parameter different than the first braid pattern. For anotherexample, the proximal end portion 12 and the distal end portion 14 mayeach include a first parameter and the intermediate portion 16 mayinclude a second parameter different than the parameter. For yet anotherexample, at least one of the proximal end portion 12, the distal endportion 14, and the intermediate portion 16 may include both a firstparameter and a second parameter different than the first parameter.Filament parameters may include, for example, filament type, filamentthickness, filament material, quantity of filaments, weave pattern,layering, wind direction, pitch, angle, crossing type, filament couplingor lack thereof, filament end treatment, weave end treatment, layeringend treatment, quantity of layers, presence or absence of welds,radiopacity, braid pattern, density, porosity, filament angle, braiddiameter, winding diameter, and shape setting.

Tubes or sheets may be cut to form strut or cell patterns, struts beingthe parts of the tube or sheet left after cutting and cells orperforations or windows being the parts cut away. A tube (e.g.,hypotube) may be cut directly, or a sheet may be cut and then rolledinto a tube. The tube or sheet may be shape set before or after cutting.The tube or sheet may be welded or otherwise coupled to itself, toanother tube or sheet, to filaments, to a graft material, etc. Cuttingmay be by laser, chemical etchant, plasma, combinations thereof, and thelike. Example cut patterns include helical spiral, weave-like, coil,individual rings, sequential rings, open cell, closed cell, combinationsthereof, and the like. In embodiments including sequential rings, therings may be coupled using flex connectors, non-flex connectors, and/orcombinations thereof. In embodiments including sequential rings, therings connectors (e.g., flex, non-flex, and/or combinations thereof) mayintersect ring peaks, ring valleys, intermediate portions of struts,and/or combinations thereof (e.g., peak-peak, valley-valley, mid-mid,peak-valley, peak-mid, valley-mid, valley-peak, mid-peak, mid-valley).The tube or sheet or sections thereof may be ground and/or polishedbefore or after cutting. Interior ridges may be formed, for example toassist with fluid flow. Parameters of the cut tube or sheet may beuniform or substantially uniform across a portion and/or across multipleportions, or may vary within a portion and/or across multiple portions.For example, the proximal end portion 12 may include a first parameterand the distal end portion 14 may include a second parameter differentthan the first parameter. For another example, the proximal end portion12 and the distal end portion 14 may each include a first parameter andthe intermediate portion 16 may include a second parameter differentthan the parameter. For yet another example, at least one of theproximal end portion 12, the distal end portion 14, and the intermediateportion 16 may include both a first parameter and a second parameterdifferent than the first parameter. Cut tube or sheet parameters mayinclude, for example, radial strut thickness, circumferential strutwidth, strut shape, cell shape, cut pattern, cut type, material,density, porosity, tube diameter, and shape setting.

In some embodiments, the perforations may provide the mesh with arelatively flexible intermediate portion and relatively stiff endportions. The supporting structure may instead be an open-cell foamdisposed within the tube.

Filaments of a stent, stent-graft, or a portion thereof, and/or strutsof a cut stent, stent-graft, or a portion thereof, may be surfacemodified, for example to carry medications such as thrombosis modifiers,fluid flow modifiers, antibiotics, etc. Filaments of a stent,stent-graft, or a portion thereof, and/or struts of a cut stent,stent-graft, or a portion thereof, may be at least partially coveredwith a coating including medications such as thrombosis modifiers, fluidflow modifiers, antibiotics, etc., for example embedded within a polymerlayer or a series of polymer layers, which may be the same as ordifferent than the polymer tube 18.

Thickness (e.g., diameter) of filaments of a stent, stent-graft, or aportion thereof, and/or struts of a cut stent, stent-graft, or a portionthereof, may be between about 0.0005 inches and about 0.02 inches,between about 0.0005 inches and about 0.015 inches, between about 0.0005inches and about 0.01 inches, between about 0.0005 inches and about0.008 inches, between about 0.0005 inches and about 0.007 inches,between about 0.0005 inches and about 0.006 inches, between about 0.0005inches and about 0.005 inches, between about 0.0005 inches and about0.004 inches, between about 0.0005 inches and about 0.003 inches,between about 0.0005 inches and about 0.002 inches, between about 0.0005inches and about 0.001 inches, between about 0.001 inches and about 0.02inches, between about 0.001 inches and about 0.015 inches, between about0.001 inches and about 0.01 inches, between about 0.001 inches and about0.008 inches, between about 0.001 inches and about 0.007 inches, betweenabout 0.001 inches and about 0.006 inches, between about 0.001 inchesand about 0.005 inches, between about 0.001 inches and about 0.004inches, between about 0.001 inches and about 0.003 inches, between about0.001 inches and about 0.002 inches, between about 0.002 inches andabout 0.02 inches, between about 0.002 inches and about 0.015 inches,between about 0.002 inches and about 0.01 inches, between about 0.002inches and about 0.008 inches, between about 0.002 inches and about0.007 inches, between about 0.002 inches and about 0.006 inches, betweenabout 0.002 inches and about 0.005 inches, between about 0.002 inchesand about 0.004 inches, between about 0.002 inches and about 0.003inches, between about 0.003 inches and about 0.02 inches, between about0.003 inches and about 0.015 inches, between about 0.003 inches andabout 0.01 inches, between about 0.003 inches and about 0.008 inches,between about 0.003 inches and about 0.007 inches, between about 0.003inches and about 0.006 inches, between about 0.003 inches and about0.005 inches, between about 0.003 inches and about 0.004 inches, betweenabout 0.004 inches and about 0.02 inches, between about 0.004 inches andabout 0.015 inches, between about 0.004 inches and about 0.01 inches,between about 0.004 inches and about 0.008 inches, between about 0.004inches and about 0.007 inches, between about 0.004 inches and about0.006 inches, between about 0.004 inches and about 0.005 inches, betweenabout 0.005 inches and about 0.02 inches, between about 0.005 inches andabout 0.015 inches, between about 0.005 inches and about 0.01 inches,between about 0.005 inches and about 0.008 inches, between about 0.005inches and about 0.007 inches, between about 0.005 inches and about0.006 inches, between about 0.006 inches and about 0.02 inches, betweenabout 0.006 inches and about 0.015 inches, between about 0.006 inchesand about 0.01 inches, between about 0.006 inches and about 0.008inches, between about 0.006 inches and about 0.007 inches, between about0.007 inches and about 0.02 inches, between about 0.007 inches and about0.015 inches, between about 0.007 inches and about 0.01 inches, betweenabout 0.007 inches and about 0.008 inches, between about 0.008 inchesand about 0.02 inches, between about 0.008 inches and about 0.015inches, between about 0.008 inches and about 0.01 inches, between about0.01 inches and about 0.02 inches, between about 0.01 inches and about0.015 inches, or between about 0.015 inches and about 0.02 inches. Otherthicknesses are also possible, including thicknesses greater than orless than the identified thicknesses. Filaments and/or struts comprisingcertain materials (e.g., biodegradable material, materials with lessrestoring force, etc.) may be thicker than the identified thicknesses.

Thicknesses of filaments and/or struts may be based, for example, on atleast one of device or device portion size (e.g., diameter and/orlength), porosity, radial strength, material, quantity of filamentsand/or struts, cut pattern, weave pattern, layering pattern, and thelike. For example, larger filament and/or strut thicknesses (e.g.,greater than about 0.006 inches) may be useful for large devices ordevice portions used to treat large vessels such as coronary vessels,mid-sized filament and/or strut thicknesses (e.g., between about 0.003inches and about 0.006 inches) may be useful for mid-sized used to treatmid-sized vessels such as peripheral vessels, and small filament and/orstrut thicknesses (e.g., less than about 0.003 inches) may be useful forsmall devices or device portions used to treat small vessels such asveins and neurological vessels.

The internal or external diameter of a stent, a stent-graft, or a firstend portion, second end portion, intermediate portion, or subportionthereof, for example taking into account filament or strut thickness,may be between about 1 mm and about 12 mm, between about 1 mm and about10 mm, between about 1 mm and about 8 mm, between about 1 mm and about 6mm, between about 1 mm and about 4 mm, between about 1 mm and about 2mm, between about 2 mm and about 12 mm, between about 2 mm and about 10mm, between about 2 mm and about 8 mm, between about 2 mm and about 6mm, between about 2 mm and about 4 mm, between about 4 mm and about 12mm, between about 4 mm and about 10 mm, between about 4 mm and about 8mm, between about 4 mm and about 6 mm, between about 6 mm and about 12mm, between about 6 mm and about 10 mm, between about 6 mm and about 8mm, between about 8 mm and about 12 mm, between about 8 mm and about 10mm, or between about 10 mm and about 12 mm. Certain such diameters maybe suitable for treating, for example, coronary vessels. The internal orexternal diameter of a stent, a stent-graft, or a portion thereof, forexample taking into account filament or strut thickness, may be betweenabout 1 mm and about 10 mm, between about 1 mm and about 8 mm, betweenabout 1 mm and about 6 mm, between about 1 mm and about 4 mm, betweenabout 1 mm and about 2 mm, between about 2 mm and about 10 mm, betweenabout 2 mm and about 8 mm, between about 2 mm and about 6 mm, betweenabout 2 mm and about 4 mm, between about 4 mm and about 10 mm, betweenabout 4 mm and about 8 mm, between about 4 mm and about 6 mm, betweenabout 6 mm and about 10 mm, between about 6 mm and about 8 mm, orbetween about 8 mm and about 10 mm. Certain such diameters may besuitable for treating, for example, veins. The internal or externaldiameter of a stent, a stent-graft, or a portion thereof, for exampletaking into account filament or strut thickness, may be between about 6mm and about 25 mm, between about 6 mm and about 20 mm, between about 6mm and about 15 mm, between about 6 mm and about 12 mm, between about 6mm and about 9 mm, between about 9 mm and about 25 mm, between about 9mm and about 20 mm, between about 9 mm and about 15 mm, between about 9mm and about 12 mm, between about 12 mm and about 25 mm, between about12 mm and about 20 mm, between about 12 mm and about 15 mm, betweenabout 15 mm and about 25 mm, between about 15 mm and about 20 mm, orbetween about 20 mm and about 25 mm. Certain such diameters may besuitable for treating, for example, peripheral vessels. The internal orexternal diameter of a stent, a stent-graft, or a portion thereof, forexample taking into account filament or strut thickness, may be betweenabout 20 mm and about 50 mm, between about 20 mm and about 40 mm,between about 20 mm and about 35 mm, between about 20 mm and about 30mm, between about 30 mm and about 50 mm, between about 30 mm and about40 mm, between about 30 mm and about 35 mm, between about 35 mm andabout 50 mm, between about 35 mm and about 40 mm, or between about 40 mmand about 50 mm. Certain such diameters may be suitable for treating,for example, aortic vessels. Other diameters are also possible,including diameters greater than or less than the identified diameters.The diameter of the device may refer to the diameter of the first endportion, the second end portion, or the intermediate portion, each ofwhich may be in expanded or unexpanded form. The diameter of the devicemay refer to the average diameter of the device when all of the portionsof the device are in either expanded or unexpanded form.

The length of a stent, a stent-graft, or a first end portion, second endportion, intermediate portion, or subportion thereof may be betweenabout 5 mm and about 150 mm, between about 5 mm and about 110 mm,between about 5 mm and about 70 mm, between about 5 mm and about 50 mm,between about 5 mm and about 25 mm, between about 5 mm and about 20 mm,between about 5 mm and about 10 mm, between about 10 mm and about 150mm, between about 10 mm and about 110 mm, between about 10 mm and about70 mm, between about 10 mm and about 50 mm, between about 10 mm andabout 25 mm, between about 10 mm and about 20 mm, between about 20 mmand about 150 mm, between about 20 mm and about 110 mm, between about 20mm and about 70 mm, between about 20 mm and about 50 mm, between about20 mm and about 25 mm, between about 25 mm and about 150 mm, betweenabout 25 mm and about 110 mm, between about 25 mm and about 70 mm,between about 25 mm and about 50 mm, between about 50 mm and about 150mm, between about 50 mm and about 110 mm, between about 50 mm and about70 mm, between about 70 mm and about 150 mm, between about 70 mm andabout 110 mm, or between about 110 mm and about 150 mm. Other lengthsare also possible, including lengths greater than or less than theidentified lengths.

The porosity of a stent, a stent-graft, or a first end portion, secondend portion, intermediate portion, or subportion thereof may be betweenabout 5% and about 95%, between about 5% and about 50%, between about 5%and about 25%, between about 5% and about 10%, between about 10% andabout 50%, between about 10% and about 25%, between about 25% and about50%, between about 50% and about 95%, between about 50% and about 75%,between about 50% and about 60%, between about 60% and about 95%,between about 75% and about 90%, between about 60% and about 75%, andcombinations thereof. The density of a stent may be inverse to theporosity of that stent. The porosity of a portion of a stent covered bya graft may be about 0%. The porosity may vary by objectives for certainportions of the stent. For example, the intermediate portion may have alow porosity to increase fluid flow through the device, while endportions may have lower porosity to increase flexibility and wallapposition.

The radial strength or compression resistance of a stent, a stent-graft,or a first end portion, second end portion, intermediate portion, orsubportion thereof may be between about 0.1 N/mm and about 0.5 N/mm,between about 0.2 N/mm and about 0.5 N/mm, between about 0.3 N/mm andabout 0.5 N/mm, between about 0.1 N/mm and about 0.3 N/mm, between about0.1 N/mm and about 0.2 N/mm, between about 0.2 N/mm and about 0.5 N/mm,between about 0.2 N/mm and about 0.3 N/mm, or between about 0.3 N/mm andabout 0.5 N/mm.

The values of certain parameters of a stent, a stent-graft, or a firstend portion, second end portion, intermediate portion, or subportionthereof may be linked (e.g., proportional). For example, a ratio of athickness of a strut or filament to a diameter of a device portioncomprising that strut or filament may be between about 1:10 and about1:250, between about 1:25 and about 1:175, or between about 1:50 andabout 1:100. For another example, a ratio of a length of a device orportion thereof to a diameter of a device or a portion thereof may bebetween about 1:1 and about 50:1, between about 5:1 and about 25:1, orbetween about 10:1 and about 20:1.

Portions of the device may include radiopaque material. For example,filaments and/or struts a stent, a stent-graft, or a first end portion,second end portion, intermediate portion, or subportion thereof maycomprise (e.g., be at least partially made from) titanium, tantalum,rhenium, bismuth, silver, gold, platinum, iridium, tungsten,combinations thereof, and the like. For another example, filamentsand/or struts of a stent, stent-graft, or a portion thereof may comprise(e.g., be at least partially made from) a material having a densitygreater than about 9 grams per cubic centimeter. Separate radiopaquemarkers may be attached to certain parts of the device. For example,radiopaque markers can be added to the proximal end of the device orparts thereof (e.g., a proximal part of the intermediate portion, aproximal part of the distal portion), the distal end of the device orparts thereof (e.g., a distal part of the intermediate portion, a distalpart of the proximal portion), and/or other parts. A radiopaque markerbetween ends of a device may be useful, for example, to demarcatetransitions between materials, portions, etc. Radiopacity may varyacross the length of the device. For example, the proximal portion couldhave a first radiopacity (e.g., due to distal portion material and/orseparate markers) and the distal portion could have a second radiopacity(e.g., due to distal portion material and/or separate markers) differentthan the first radiopacity.

In some embodiments, the device includes a polymer tube, and nosupporting structure is provided. The intermediate portion of such adevice may be relatively more flexible than the end portions by, forexample, decreasing the wall thickness of the polymer tube within theintermediate portion.

When a mesh or other supporting structure is provided in combinationwith a polymer tube, the supporting structure may be located around theoutside of the tube, in the inner bore of the tube, or embedded within awall of the tube. More than one supporting structure may be provided, inwhich case each supporting structure may have a different location withrespect to the tube.

One or both of the end portions of the device may include anchoringelements such as hooks, protuberances, or barbs configured to grasp orgrip inner sidewalls of a blood vessel. The radial force of the endportions after expansion may be sufficient to grasp or grip innersidewalls of a blood vessel without anchoring elements.

There need not be a well-defined transition between the intermediate andend portions. For example, mesh type, material, wall thickness,flexibility, etc. may gradually change from an end portion toward anintermediate portion or from an intermediate portion toward an endportion.

The flexibility of the device may increase gradually when moving from anend portion towards the intermediate portion, for example as describedwith respect to the devices 34, 40. The change in flexibility may be dueto change in mesh density (e.g., winding density, window size), tubethickness, or other factors. The flexibility of the device may beuniform or substantially uniform along the entire length of the supportstructure (e.g., stent), or along certain portions of the supportstructure (e.g., along an entire end portion, along the entireintermediate portion, along one end portion and the intermediate portionbut not the other end portion, etc.).

While the devices described herein may be particularly suitable for useas a transvascular shunt in percutaneous surgery, the devices could beused in many other medical applications. For example, the devices couldbe used in angioplasty for the treatment of occluded blood vessels withtortuous or kinked paths, or where the vessels may be subject todeflection or deformation at or near the position of the stent. Thestent could also be used for the repair of damaged blood vessels, forexample in aortic grafting procedures or after perforation during apercutaneous procedure. In certain such cases, the intermediate portionof the device can allow the device to conform to the shape of the bloodvessel and to deform in response to movement of the vessel with reducedrisk of fatigue failure while remaining fixed or anchored in position bythe end portions. For another example, the devices could be used to forma shunt between a healthy artery and a healthy vein for dialysis accessand/or access for administration of medications (e.g., intermittentinjection of cancer therapy, which can damage vessels).

While the devices described herein may be used in applications in whichthe fluid that flows through the device is a liquid such as blood, thedevices could be used in applications such as tracheal or bronchialsurgery where the fluid is a gas, such as air. In some embodiments, thefluid may contain solid matter, for example emboli or, in gastricsurgery where the fluid includes food particles.

The ranges disclosed herein also encompass any and all overlap,sub-ranges, and combinations thereof. Language such as “up to,” “atleast,” “greater than,” “less than,” “between,” and the like includesthe number recited. Numbers preceded by a term such as “about” or“approximately” include the recited numbers. For example, “about 10 mm”includes “10 mm.” Terms or phrases preceded by a term such as“substantially” include the recited term or phrase. For example,“substantially parallel” includes “parallel.”

EXAMPLE EMBODIMENTS

The following example embodiments identify some possible permutations ofcombinations of features disclosed herein, although other permutationsof combinations of features are also possible.

-   -   1. A method of diverting fluid flow from a first passage to a        second passage, the method comprising:        -   deploying a device in a third passage between the first            passage and the second passage, the device comprising;            -   a first end portion having a first end diameter;            -   a second end portion having a second end diameter larger                than the first end diameter;            -   an intermediate portion between the first end portion                and the second end portion, the intermediate portion                tapering between the first end portion and the second                end portion; and            -   a graft material coupled to at least the intermediate                portion;        -   expanding the first end portion against sidewalls of the            first passage; and        -   expanding the second end portion against sidewalls of the            second passage.    -   2. The method of Embodiment 1, wherein the first passage is an        artery and the second passage is a vein.    -   3. The method of Embodiment 2, wherein the first passage is a        coronary artery and the second passage is a coronary vein.    -   4. The method of Embodiment 2, wherein the first passage is a        peripheral artery and the second passage is a peripheral vein.    -   5. The method of any one of Embodiments 1-4, further comprising        dilating the third passage.    -   6. The method of Embodiment 5, wherein dilating the third        passage comprises expanding the intermediate portion.    -   7. The method of any one of Embodiments 1-6, wherein the first        passage is substantially parallel to the second passage.    -   8. The method of any one of Embodiments 1-7, wherein the        intermediate portion is conformable to an “S” shape.    -   9. The method of any one of Embodiments 1-8, wherein expanding        the first end portion and the second end portion comprises        allowing self-expansion of the first end portion and the second        end portion.    -   10. The method of any one of Embodiments 1-9, wherein expanding        the first end portion and the second end portion comprises        balloon expanding at least one of the first end portion and the        second end portion.    -   11. The method of any one of Embodiments 1-10, wherein expanding        one of the first end portion and the second end portion        comprises allowing self-expansion of the one of the first end        portion and the second end portion and wherein expanding the        other of the first end portion and the second end portion        comprises balloon expanding the other of the first end portion        and the second end portion.    -   12. The method of any one of Embodiments 1-11, further        comprising expanding the intermediate portion.    -   13. A device comprising:        -   a first end portion having a first end diameter;        -   a second end portion having a second end diameter smaller            than the first end diameter;        -   an intermediate portion between the first end portion and            the second end portion, the intermediate portion tapering            between the first end portion and the second end portion;            and        -   a graft material coupled to at least the intermediate            portion.    -   14. The device of Embodiment 13, wherein at least one of the        first end portion and the second end portion is substantially        cylindrical.    -   15. The device of Embodiment 14, wherein the first end portion        is substantially cylindrical and the second end portion is        substantially cylindrical.    -   16. The device of any one of Embodiments 13-15, wherein the        first end portion tapers between the first end diameter and the        intermediate portion, or wherein the second end portion tapers        between the second end diameter and the intermediate portion.    -   17. The device of any one of Embodiments 13-15, wherein the        first end portion tapers between the first end diameter and the        intermediate portion and the second end portion tapers between        the second end diameter and the intermediate portion.    -   18. The device of any one of Embodiments 13-17, wherein the        first end portion comprises a first type of material, the second        end portion comprises a second type of material, and the        intermediate portion comprises a third type of material.    -   19. The device of Embodiment 18, wherein the first type of        material comprises a first cut material, the second type of        material comprises a second cut material, and the third type of        material comprises filaments.    -   20. The device of Embodiment 19, wherein the first cut material        comprises a chromium cobalt alloy, the second cut material        comprises nitinol, and the filaments comprises nitinol.    -   21. The device of Embodiment 18, wherein the first type of        material comprises a cut material, the second type of material        comprises the cut material, and the third type of material        comprises filaments.    -   22. The device of Embodiment 21, wherein the cut material        comprises nitinol and the filaments comprises nitinol.    -   23. The device of any one of Embodiments 13-22, wherein at least        one of the first end portion, the second end portion, the        intermediate portion, and the graft material comprises a        bioabsorbable material.    -   24. The device of any one of Embodiments 13-23, wherein at least        some of the graft material is outside the intermediate portion,        at least some of the graft material is inside the intermediate        portion, or at least some of the graft material is embedded        within the intermediate portion.    -   25. The device of any one of Embodiments 13-24, wherein the        device is capable of maintaining fluid flow between a first        passage in which the first end portion is anchored and a second        passage in which the second end portion is anchored.    -   26. The device of Embodiment 25, wherein the first passage is        substantially parallel to the second passage.    -   27. The device of Embodiment 25 or 26, wherein the intermediate        portion is conformable to an “S” shape.    -   28. A device comprising:        -   a first end portion comprising a first material;        -   a second end portion comprising a second material different            than the first material;        -   an intermediate portion between the first end portion and            the second end portion; and        -   a graft material coupled to at least the intermediate            portion.    -   29. The device of Embodiment 28, wherein the first material        comprises nitinol and the second material comprises chromium        cobalt.    -   30. The device of Embodiment 28 or 29, wherein the first        material comprises nitinol and the second material comprises        stainless steel.    -   31. The device of any one of Embodiments 28-30, wherein the        first end portion comprises cut struts and the second end        portion comprises filaments.    -   32. The device of any one of Embodiments 28-31, wherein the        first end portion comprises cut struts and the second end        portion comprises cut struts.    -   33. The device of any one of Embodiments 28-33, wherein the        first material comprises an alloy and the first end portion        comprises struts or filaments having a first thickness, and        wherein the second material comprises the alloy and the second        end potion comprises struts or filaments having a second        thickness different than the first thickness.    -   34. The device of any one of Embodiments 28-33, wherein the        intermediate portion comprises a third material.    -   35. The device of Embodiment 34, wherein the third material        comprises nitinol.    -   36. The device of any one of Embodiments 28-35, wherein the        intermediate portion comprises filaments.    -   37. The device of any one of Embodiments 28-36, wherein the        intermediate portion comprises cut struts.    -   38. The device of any one of Embodiments 28-37, wherein at least        one of the first end portion and the second end portion is        substantially cylindrical.    -   39. The device of any one of Embodiments 28-38, wherein at least        one of the first end portion, the second end portion, the        intermediate portion, and the graft material comprises a        bioabsorbable material.    -   40. The device of any one of Embodiments 28-39, wherein at least        some of the graft material is outside the intermediate portion,        at least some of the graft material is inside the intermediate        portion, or at least some of the graft material is embedded        within the intermediate portion.    -   41. The device of any one of Embodiments 28-41, wherein the        graft material is coupled to at least one of the first end        portion and the second end portion.    -   42. The device of any one of Embodiments 28-42, wherein the        device is capable of maintaining fluid flow between a first        passage in which the first end portion is anchored and a second        passage in which the second end portion is anchored.    -   43. The device of Embodiment 42, wherein the first passage is        substantially parallel to the second passage.    -   44. The device of Embodiment 42 or 43, wherein the intermediate        portion is conformable to an “S” shape.    -   45. A device comprising:        -   a support structure comprising            -   a first end portion;            -   a second end portion;            -   an intermediate portion between the first end portion                and the second end portion, at least one of the first                end portion, the second end portion, and the                intermediate portion being comprising cut struts and at                least one of the first end portion, the second end                portion, and the intermediate portion comprising                filaments; and        -   a graft material coupled to at least the intermediate            portion.    -   46. The device of Embodiment 45, wherein the first end portion        and the second end portion comprise cut struts and the        intermediate portion comprises filaments.    -   47. The device of Embodiment 45 or 46, wherein at least some of        the graft material is outside the intermediate portion, at least        some of the graft material is inside the intermediate portion,        or at least some of the graft material is embedded within the        intermediate portion.    -   48. The device of any one of Embodiments 45-47, wherein the        graft material is coupled to at least one of the first end        portion and the second end portion.    -   49. The device of any one of Embodiments 45-48, wherein the        device is capable of maintaining fluid flow between a first        passage in which the first end portion is anchored and a second        passage in which the second end portion is anchored.    -   50. The device of Embodiment 49, wherein the first passage is        substantially parallel to the second passage.    -   51. The device of Embodiment 49 or 50, wherein the intermediate        portion is conformable to an “S” shape.

What is claimed is:
 1. A method of forming a channel between a firstvessel and a second vessel, the method comprising: forming a passagebetween the first vessel and the second vessel, wherein the first vesselis an artery and the second vessel is a vein; deploying a device in thefirst vessel, the second vessel, and the passage, the device comprising:a longitudinal axis; a first end portion having a first radialstiffness, the first end portion having a first length along thelongitudinal axis; a second end portion having a second radialstiffness, the second end portion having a second length along thelongitudinal axis; and an intermediate portion between the first endportion and the second end portion, the intermediate portion having athird radial stiffness less than the first radial stiffness and thesecond radial stiffness, the intermediate portion having a third lengthalong the longitudinal axis; wherein deploying the device in the firstvessel, the second vessel, and the passage comprises: expanding thefirst end portion against sidewalls of the first vessel; expanding thesecond end portion against sidewalls of the second vessel; and expandingthe intermediate portion in the passage, wherein expanding theintermediate portion comprises the dilating the passage.
 2. The methodof claim 1, wherein expanding at least one of the first end portion andthe second end portion comprises allowing self-expansion of at least oneof the first end portion and the second end portion.
 3. The method ofclaim 1, wherein expanding at least one of the first end portion and thesecond end portion comprises balloon expanding at least one of the firstend portion and the second end portion.
 4. The method of claim 1,further comprising a polymer material coupled to at least theintermediate portion, wherein the first end portion has a firstdiameter, wherein the first end portion is substantially cylindrical,wherein the second end portion has a second diameter larger than thefirst diameter, and wherein the intermediate portion tapers between thefirst end portion and the second end portion.
 5. The method of claim 1,wherein forming the passage comprises: inserting a first catheter in thefirst vessel upstream of an occlusion site in the first vessel; anddeploying a needle from the first catheter, through tissue between thefirst vessel and the second vessel, and into the second vessel, andwherein deploying the device in the first vessel, the second vessel, andthe passage further comprises: inserting a guidewire through the needle;retracting the needle and the catheter; guiding a delivery cathetercarrying the device to the passage using the guidewire; and deployingthe device from the delivery catheter.
 6. A method of forming a channelbetween a first vessel and a second vessel, the method comprising:deploying a device in the first vessel, the second vessel, and a passagebetween the first vessel and the second vessel, the device comprising: alongitudinal axis; a first end portion having a first radial stiffness;a second end portion having a second radial stiffness; and anintermediate portion between the first end portion and the second endportion, the intermediate portion having a third radial stiffness lessthan the first radial stiffness and the second radial stiffness; whereindeploying the device in the first vessel, the second vessel, and thepassage comprises: expanding the first end portion against sidewalls ofthe first vessel; expanding the second end portion against sidewalls ofthe second vessel; and expanding the intermediate portion in thepassage, wherein expanding the intermediate portion comprises thedilating the passage.
 7. The method of claim 6, wherein expanding atleast one of the first end portion and the second end portion comprisesallowing self-expansion of at least one of the first end portion and thesecond end portion.
 8. The method of claim 6, wherein expanding at leastone of the first end portion and the second end portion comprisesballoon expanding at least one of the first end portion and the secondend portion.
 9. The method of claim 6, wherein the first vessel is anartery and the second vessel is a vein.
 10. The method of claim 6,further comprising a polymer material coupled to at least theintermediate portion, wherein the first end portion has a firstdiameter, wherein the first end portion is substantially cylindrical,wherein the second end portion has a second diameter larger than thefirst diameter, and wherein the intermediate portion tapers between thefirst end portion and the second end portion.
 11. The method of claim 6,further comprising forming the passage between the first vessel and thesecond vessel, wherein forming the passage comprises: inserting a firstcatheter in the first vessel upstream of an occlusion site in the firstvessel; and deploying a needle from the first catheter, through tissuebetween the first vessel and the second vessel, and into the secondvessel, and wherein deploying the device in the first vessel, the secondvessel, and the passage further comprises: inserting a guidewire throughthe needle; retracting the needle and the catheter; guiding a deliverycatheter carrying the device to the passage using the guidewire; anddeploying the device from the delivery catheter.
 12. A method of forminga channel between a first vessel and a second vessel, the methodcomprising: deploying a device in the first vessel, the second vessel,and a passage between the first vessel and the second vessel, the devicecomprising: a first end portion having a first radial stiffness; asecond end portion having a second radial stiffness; and an intermediateportion longitudinally between the first end portion and the second endportion, the intermediate portion having a third radial stiffness lessthan the first radial stiffness and the second radial stiffness; whereindeploying the device in the first vessel, the second vessel, and thepassage comprises: expanding the first end portion against sidewalls ofthe first vessel; expanding the second end portion against sidewalls ofthe second vessel; and expanding the intermediate portion in thepassage.
 13. The method of claim 12, wherein the first vessel is anartery and the second vessel is a vein.
 14. The method of claim 12,comprising dilating the passage.
 15. The method of claim 12, whereinexpanding the first end portion and the second end portion comprisesallowing self-expansion of at least one of the first end portion and thesecond end portion.
 16. The method of claim 12, wherein expanding thefirst end portion and the second end portion comprises balloon expandingat least one of the first end portion and the second end portion. 17.The method of claim 12, further comprising forming the passage, whereinforming the passage comprises deploying a needle between the firstvessel and the second vessel.
 18. The method of claim 17, whereindeploying the device in the first vessel, the second vessel, and thepassage further comprises: inserting a guidewire through the needle;retracting the needle; guiding a delivery catheter carrying the deviceto the passage using the guidewire; and deploying the device from thedelivery catheter.
 19. The method of claim 12, further comprising apolymer material coupled to at least the intermediate portion, whereinthe first end portion has a first diameter, wherein the first endportion is substantially cylindrical, wherein the second end portion hasa second diameter larger than the first diameter, and wherein theintermediate portion tapers between the first end portion and the secondend portion.
 20. The method of claim 19, wherein the second end portiontapers between the intermediate portion and the second diameter.